1. Field of the Invention
The present invention generally relates to hinges and, more particularly, to a hinged limb immobilizer.
2. Description of the Prior Art
A frequently used method of post-operative ligament rehabilitation involves allowing restrictive but progressive motion of a limb, such as an arm, leg, or foot. Hinged limb immobilizers have been developed which allow the range of flexion-extension to be selectively set. "Flexion" refers to the act of bending a limb so as to decrease the angle formed by the limb, as in the act of flexing one's arm muscle. "Extension" means the opposite of flexion, as in the act of fully extending one's arm or leg. Two factors primarily determine the effectiveness of these immobilizers: (1) the security of the "limit stops" which define the allowable range of motion; and (2) the method of setting and adjusting these stops. Limit stops are typically either friction stops or positive stops. Friction stops provide the least security, since continued impact of the hinge against the stop can result in loosening, and gradual changes in the preset allowable range of motion. Positive stops are subject to bending and breakage through continued impact loading if the stops are small enough to allow desirable narrow incremental adjustments. If large enough for sufficient mechanical integrity, positive stops often fail to provide the desired level of adjustability. Current means for setting the limit stops may involve removable components which can be lost, or may require special tools which could be misplaced or otherwise unavailable when needed. Methods of adjustment may also be cumbersome or confusing for the wearer of the brace. Each of the preceding situations can result in compromised treatment, which can subsequently cause reinjury or impairment of the healing process.
The applicants are aware of the following U.S. patents concerning limb immobilizers.
__________________________________________________________________________ Issue Date Inventor Title __________________________________________________________________________ U.S. Pat. No. 4,620,532 Nov. 4, 1986 Houswerth ADJUSTMENT DEVICE FOR AN ARTICULATED JOINT BRACE 4,370,977 Feb. 1, 1983 Mauldin, et al. KNEE AND ELBOW BRACE 4,554,913 Nov. 26, 1985 Womack, et al. ADJUSTABLE JOINT FOR A KNEE BRACE 4,337,764 Jul. 6, 1982 Lerman ADJUSTABLE MOTION BRACE 4,506,661 Mar. 26, 1985 Foster BALANCED SUSPENSION KNEE BRACE 4,487,200 Dec. 11, 1984 Feanny, et al. BRACE FOR KNEE GER Pat. No. 412,362 Apr. 17, 1925 Steinmann KUNSTLICHES KNIEGELENK ZUR UNTERSTUTZUNG DES NATURLICHEN KNIEGELENKES (ARTIFICIAL KNEE- JOINT FOR SUPPORTING A NATURAL KNEE JOINT) __________________________________________________________________________
Houswerth, Mauldin, et.al., and Womack, et.al., all relate to joint braces using positive stop mechanisms. Houswerth discloses an adjustment device for an articulated joint brace having positive stops in conjunction with slide elements. It is the closest reference to the present invention, but requires the use of special tools to adjust the device. In addition, Houswerth does not include the three-point locking mechanism of the present invention. Mauldin, et.al., teaches a knee and elbow brace using a threaded bolt as a positive stop and also using a spring means in conjunction with the brace for assisting extension of the knee. Womack, et.al., relates to an adjustable joint for a knee brace with positive stops.
Lerman and Foster both teach knee braces using friction stops. Feanny, et.al., generally, relates to a brace for a knee and is not seen to be any more relevant than the previously discussed references.
Finally, Steinmann relates to an artificial knee-joint for supporting a natural knee. Although stops are provided, they appear to be positive stops and, moreover, do not appear to be adjustable.
Each of the prior art references cited above suffer from the disadvantages previously discussed. Applicants are unaware of any prior art that accomplishes the objects of the present invention. Consequently, a need exists for the invented hinged limb immobilizer.